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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 8: Tìn x biết a, (x-2)² + (x-1)² + (x-3)(x+3) – 3x² = -8 b, 2021x(x-2020) – x+2020=0

Home/ Toán Lớp 8: Tìn x biết a, (x-2)² + (x-1)² + (x-3)(x+3) – 3x² = -8 b, 2021x(x-2020) – x+2020=0

Toán Lớp 8: Tìn x biết a, (x-2)² + (x-1)² + (x-3)(x+3) – 3x² = -8 b, 2021x(x-2020) – x+2020=0

Tháng Sáu 4, 2022 Toán học 2 Comments 0 views

Toán Lớp 8: Tìn x biết
a, (x-2)² + (x-1)² + (x-3)(x+3) – 3x² = -8
b, 2021x(x-2020) – x+2020=0

Comments ( 2 )

  1. giangnguyen33
    giangnguyen33
    4 Tháng Sáu, 2022 at 6:40 sáng
    Reply
     

    toan-lop-8-tin-biet-a-2-1-3-3-3-8-b-2021-2020-2020-0

  2. diemchau
    diemchau
    4 Tháng Sáu, 2022 at 6:40 sáng
    Reply
    a) (x-2)^2+(x-1)^2+(x-3)(x+3)-3x^2=-8
    ⇔x^2-4x+4+x^2-2x+1+x^2-9-3x^2+8=0
    ⇔-6x+4=0
    ⇔-6x=-4
    ⇔x=2/3
    Vậy x=2/3
    b) 2021x(x-2020)-x+2020=0
    ⇔2021x(x-2020)-(x-2020)=0
    ⇔(x-2020)(2021x-1)=0
    ⇔\(\left[ \begin{array}{l}2020-x=0\\2021x-1=0\end{array} \right.\) 
    ⇔\(\left[ \begin{array}{l}x=2020\\x=\dfrac{1}{2021}\end{array} \right.\) 
    Vậy x=2020 hoặc x=1/(2021)
     

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222-9+11+12:2*14+14 = ? ( )

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